DESCRIPTION: Using comprehensive data from New Jersey, the investigators propose a series of studies analyzing birth outcomes in the late 1980s and early 1990s. They will merge individual level data with contextual factors, do detailed analysis of racial, ethnic, and immigrant groups, and evaluate the effectiveness of a statewide Medicaid prenatal care program. The results will indicate which individual, contextual, and programmatic factors have the most impact on birth outcomes, allowing interventions to be targeted to specific groups Given the high social and economic costs of late or no prenatal care, low birth weight, and infant mortality, the findings will be of interest to both the scientific and policy communities. Part I will analyze the effects of individual demographic, lifestyle, and socioeconomic factors on prenatal care use, birth weight, hospital costs, and infant mortality using individual-level data on all births in New Jersey between 1989 and 1992. The investigators will link all mothers to census tract level socioeconomic and segregation measures. Using robust multilevel modeling techniques that control for correlated errors, they will examine the additive and interactive effects of context. The investigators will compare the patterns for blacks and whites, focusing on whether differences in residential context help explain the racial differentials in birth outcomes. Part II focuses in immigration and birth outcomes. Little is known about the health status of different immigrant groups or their use of health-related resources. The data allow the investigators to identify mothers in a number of different ethnic and immigrant subgroups, such as foreign and US.-born women who are Mexican, Cuban, Chinese, Filipino, etc. New Jersey is an appropriate choice because of the variety of immigrant groups who live in the state. The investigators will examine whether mother's place of birth and ethnic group have effects when the investigators control for other risk factors such as poverty and residential characteristics. Part III evaluates the effectiveness of Health Start, a program of enriched prenatal and health support services for pregnant women on Medicaid. To ascertain the overall program impact, the investigators will compare outcomes of women in the program with those of eligible women who did not participate. To understand which components of Health Start are most effective, they will also analyze variation in birth outcomes within the program.